Neonatal herpes simplex virus infection after cesarean section with intact amniotic membranes.

We describe a preterm neonate delivered by cesarean section with intact membranes who had herpes simplex virus (HSV) encephalitis at 9 days of age and whose twin with a separate amniotic membrane that was pierced for insertion of a fetal scalp electrode simultaneously had HSV infection of the scalp. That no histologic evidence of HSV infection was seen in either placenta suggests the potential for HSV penetration of intact amniotic membranes as a mode of transmission of HSV to the neonate. Although the extent of risk of HSV infection in a second twin remains unclear, we believe that when infection is suspected in one of a set of twins, appropriate cultures should be obtained from both infants, and acyclovir therapy should be considered for both.